Obstructive sleep apnea (OSA) is a Sleep disorder with partial or complete cessation of breathing during one's sleep. This sleep disorder is currently treated by methods such as a surgery, oral appliance therapy, negative pressure to pull soft palate and tongue forward, implantable devices that keep the airway open during sleep by stimulating the hypoglossal nerve, strips for nose for expiratory positive airway pressure, Positive Air Pressure (PAP) therapy or a combination involving several methods. PAP therapies are also employed to treat other medical and respiratory disorders, such as Cheynes-Stokes respiration, congestive heart failure, and stroke. A common PAP device comprises a flow generator (e.g., a blower) that delivers gas via delivery conduit (hollow tube) to an individual interface. It is also known to deliver the PAP as a continuous positive airway pressure (CPAP), a variable airway pressure, such as bi-level pressure (Bi-PAP) that varies with the individual's respiratory cycle or an auto-titrating pressure (APAP) that varies with the monitored condition of the individual. Nasal, oral-nasal and full face masks are common interfaces utilized for delivering PAP to the individual's airway.
These masks can be uncomfortable due to improper fit, tight straps to hold mask in place, skin irritation at points of contact, dryness of throat cause claustrophobia, excessive PAP pressure and are a major factor in individual therapy non-compliance. Also the PAP machines can be noisy. Studies show individual non-compliance for PAP therapy from 29 to over 83%.
Obstructive sleep apnea (OSA) is a Sleep disorder with partial cessation (hypopnea) or complete cessation (apnea) of breathing during one's sleep. This sleep disorder is diagnosed and analyzed by a technician monitored overnight sleep study in a sleep laboratory setting (Polysomnography or PSG) with multiple physiological parameters and more recently by Home Sleep Testing devices with limited parameters.
The federal Center for Medicare and Medicaid Services (CMS) has provided guidance for various types of sleep studies based on number of parameters and whether study is attended by Sleep technician or is unattended. A brief summary of the classification system for sleep studies based on these guidelines is provided below.
Most of the current Home Sleep Testing (HST) devices are worn on chest while current device of invention is only device which is worn in mouth. It is very comfortable, convenient, small in size and provide for more information due to proximity of several sensors to nose and mouth where actual sleep disturbances events should be measured.
Type I HST devices using in attended sleep studies performed in a sleep lab and monitored by a sleep technician with full sleep staging (i.e monitoring the transition through the various sleep stages). Typically, Type I devices include the following channels (parameters): EEG (electroencephalogram), EMG (electromyogram —chin and Limb), EOG (electrooculogram), respiratory airflow (with oronasal flow monitors), respiratory effort (Thorax and Abdomen), oxygen saturation (oximetry), ECG (electrocardiography), snoring sounds, and body position—additional channels for CPAP/Bi PAP levels, CO2, pH, pressure etc.
Type II Home sleep test (HST) devices use a portable monitor, performed without any sleep technician monitoring the study, with at least 7 channels or parameters. Type II devices typically include at the very least the following Parameters: EEG, EOG, ECG/heart rate, EMG, Airflow, Respiratory effort, Oxygen saturation. Type III Home sleep tests (HST) use a portable monitor unattended with a minimum of 4 channels. Type III devices usually include the following parameters: 2 respiratory movement/airflow, 1 ECG/heart rate, 1 oxygen saturation. Type IV Home sleep test (HST) with Type IV portable monitor, unattended with a minimum of 3 channels. Type IV devices must allow parameters that allow direct calculation of an AHI (Apnea Hypopnea Index) or RDI (Respiratory Disturbance Index) as the result of measuring airflow or thoracoabdominal movement. The RDI is defined as the average number of respiratory disturbances.
Alternately devices that record other information to derive AHI or RDI must be approved by CMS through the review of published peer reviewed medical literature. It is very expensive to perform the traditional attended PSG sleep studies in sleep labs (Type I) to diagnose for OSA. Patients have difficulty getting to sleep in a unfamiliar surrounding with various wires connected to their limbs and head and being continuously watched and monitored. This created a need for a simpler and cheaper way to diagnose for OSA and led to the development of portable sleep monitors—Home Sleep Testing machine (HST) complying with the CMS guidelines and offering results comparable to that of PSG in a home setting.